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What is a change in the structure of a chromosome?
Structural Abnormalities: A chromosome’s structure can be altered in several ways. Deletions: A portion of the chromosome is missing or deleted. Duplications: A portion of the chromosome is duplicated, resulting in extra genetic material. Translocations: A portion of one chromosome is transferred to another chromosome.
What are errors that occur in genes called?
A mutation is a change that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.
What type of mutation changes the structure of chromosomes?
Somatic mutations occur in other body cells. Chromosomal alterations are mutations that change chromosome structure. Point mutations change a single nucleotide. Frameshift mutations are additions or deletions of nucleotides that cause a shift in the reading frame.
How does changes in chromosome structure affect gene expression?
Bottom: chromosome rearrangements may disrupt loops that occur between genes in multigene complexes, causing hierarchical gene expression effects. In this example, the association with gene 1 at a site of transcription causes gene 2 to associate, which in turn causes gene 3 to do the same.
What are structural changes to genes?
Structural changes can occur during the formation of egg or sperm cells, in early fetal development, or in any cell after birth. Pieces of DNA can be rearranged within one chromosome or transferred between two or more chromosomes.
How are genes mutated?
Mutations can result from DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses. Germ line mutations occur in the eggs and sperm and can be passed on to offspring, while somatic mutations occur in body cells and are not passed on.
Which mutation changes the number of chromosomes in the cell?
Aneuploidy: Extra or missing chromosomes. Changes in a cell’s genetic material are called mutations. In one form of mutation, cells may end up with an extra or missing chromosome. Each species has a characteristic chromosome number, such as 46 chromosomes for a typical human body cell.